U.S. Pat. No. 5,317,036 teaches the gas-phase polymerization of olefins with catalysts in liquid form. In such systems resin particle size can be controlled by spraying the liquid catalyst into a zone which is substantially free of resin as disclosed in pending U.S. patent application Ser. No. 08/659,764, filed on Jun. 6, 1996, now U.S. Pat. No. 5,693,727, which is incorporated herein by reference. This process allows a brief period of time for the spray droplets to undergo evaporation and polymerization before contacting the polymer particles already in the reactor, thus reducing the tendency for the droplets to adhere to the already formed particles. The "particle-lean" zone preferably is created by feeding a jet of heated monomer or cycle gas into the side of the reactor.
However, such feed systems often yield particle agglomerates which restrict reactor operability. These particles exhibit a flaky or hollow sphere morphology and result in polymer bulk densities below 160 kg/m.sup.3. These particles have a high ratio of cross section to mass and are readily entrained out the top of the fluidized bed, and thereby accumulate in the cycle gas cooler, the compressor suction screen, and the distributor plate. These particles also restrict the flow of resin out of the reactor and in the downstream conveying lines. Avoidance of these types of particles is essential for commercial operation of catalysts in a liquid form.